Capsules are widely used for the products of medicines, dietary supplements and functional foods. Currently in the market, the main material used to manufacture capsule products is gelatin—a product made from animal bones and the skins through hydrolyzation process. Gelatin is a biological triplex structure macromolecule with good biological compatibility and physicochemical properties. The unique molecular structure of the gelatin, however, leads to some disadvantages in its application, one of which is that the gelatin capsule may become less soluble in water as gelatin is easy to crosslink with aldehyde compound, reducing sugar compound, and Vitamin C, resulting in capsule shell disintegration and delay in the dissolving-out of capsule content; another disadvantage is that it produces electrostatic charge accumulation in dry condition, which has negative influences on subsequent processing; finally, if the gelatin capsule is stored in low humidity environment for long time, it may become fragile and easily broken. In addition, because of the animal source component present in gelatin, it is not welcomed by certain groups of people with various faith and religious beliefs. Therefore, it is necessary to research and develop new materials to replace gelatin—the traditional raw material of capsules.
As plant capsule is becoming one of the fastest growing products in pharmaceutical market, the plant materials like gellan gum, carrageenan, and xanthan gum have been used as to study the preparation of the substitute products of gelatin capsules. The starch, with good film-forming properties, is one of the most important food raw materials and has been widely used in the field of food and medicine. With the advantages of rich sources and low price, starch is regarded as a most promising substitute of the raw material of capsules.
Most of the technologies applied in the preparation of starch capsules reported nowadays are similar to the traditional dip forming process to manufacture gelatin capsules. As the gel properties of starch itself can hardly meet the requirements of manufacturing process of capsules, it is, in existing preparation technology, necessary to add certain gel to improve the processing performance in the preparation of starch-based capsules
It has been a major research area to improve the mechanical properties and stability of starch-based material. In addition to starch modification, other processing technologies of polymer materials like blending and compounding are also widely used to manufacture starch-based material. In recent years, self-reinforced composites, with perfect material interface, simple chemical structure, and high value-added recycled waste, has attracted wide attention. For Medical biodegradable materials, it is extremely important to use the composite developed by single raw material, because any enhancing or modifying additive is likely to affect the biocompatibility or biodegradability of the main raw material; as a medicinal capsule, the less the amount of additive used, the better. This invention relates to a process for preparing self-reinforced starch composite that can be used to replace the gelatin as the raw material of capsules.